With large, and relatively deep, opencut mining operations, it has been known to load material onto trucks at the pit floor by means of backhoes, shovels or front end loaders, with or without an intervening feeder breaker or other crushing device, which trucks transport the material uphill from the pit via a series of roads cut into the pit area. However, as trucking costs increase and the distances which are required to travel increase with increasing pit depths, such a mode of material transportation is no longer favoured and as a substitute therefore large, mobile, steep angle conveyor systems have been developed onto which the material is loaded at the pit floor or lower bench and conveyed up the bench face to the upper bench for transportation away from the pit by trucks or other conveyor systems.
One known steep angle conveyor involves relatively large equipment adapted to move along the upper bench lifting material from the lower bench up the bench face and is fed by a backhoe, shovel or front end loader via a feeder breaker or other crushing device. The requirement for a relatively long boom supporting the conveyor and extending down the bench face requires the main support structure positioned on the upper bench on tracks for movement along the upper bench to be relatively large in order to support the boom and counteract its weight. The resulting equipment is particularly heavy and costly, whilst also being difficult to manouevre when required to be shifted from one location to another. In addition the length of the boom supporting the conveyor down the bench face cannot be easily altered to cope with variations in depth/angle orientations.
In another known proposal the boom supporting the conveyor is supported at both the upper and lower levels of the bench by movable track assemblies to form a mobile bridge conveyor moving along the bench face and onto the lower end of which the material is loaded. However, once again having support at the lower as well as the upper level of the bench makes it difficult to manouevre the equipment from one location to another and once again the length and angle of the conveyor is not easily varied.
It is therefore an object of the present invention to provide a mobile elevator conveyor which overcomes, or at least minimizes, the disadvantages with known mobile elevated conveyors of the type discussed above.